Speaker
Description
A new axiom in QFT due to Kontsevich & Segal (https://arxiv.org/abs/2105.10161) which replaces the usual causality axiom by the requirement that the theory be well-defined on a special set of "allowable" complex metrics, has been suggested by Witten (https://arxiv.org/abs/2111.06514) to be elevated to a criterion in quantum gravity which distinguishes saddle points that could contribute to the semiclassical expansion of the gravitational path integral. In our recent (https://arxiv.org/abs/2305.15440) and ongoing work we explore this proposal in the context of the no-boundary wave function of the universe, finding among others that the criterion selects inflationary histories with a small tensor-to-scalar ratio in their CMB spectrum, in line with observations. This theoretical prior on observations in cosmology could give deep insights into the quantum state of the universe. The point of this talk is to summarize the above and explain what are the open questions.
Link to publication (if applicable)
https://arxiv.org/abs/2305.15440
